For decades, time domain reflectometry has been used to measure the electrical reflections that result from an electrical signal traveling through a transmission environment of some kind. This environment could include, for example, a circuit board trace, a cable electrical connector, and the like. A time domain reflectometer instrument sends an electrical pulse through the medium, and then compares the returning reflections from the unknown media, such as a transmission wire, multi-conductor or data transfer cable, to those produced by a standard impedance transmission wire, multi-conductor or data transfer cable, for example. In normal practice, the time domain reflectometer which is selected, displays the voltage wave form that is reflected, and then returns when a fast step, incident signal is propagated down an electrical conductor. The resulting wave form is the combination of the incident step, and any electrical reflections which are generated when the incident step signal encounters impedance variations along the transmission line.
Impedance tolerances are part of the electrical specifications for many of today's complex digital system components. Still further, in some assemblies, such as highly advanced aircraft, that are used, for example, in military applications, it is necessary to locate possible malfunctions in such assemblies in a rapid manner in order to put an aircraft back into proper working condition. It has long been known that time domain reflectometry or (TDR) can be used to determine an amplitude of a reflected signal. Still further it has been known that the distance to a structure producing a reflecting impedance can also be determined from the time that it takes for an electrical pulse to return to the measuring instrument which has been selected.
While these aforementioned TDR devices, as utilized heretofore, have operated with varying degrees of success, problems persist with their usefulness in certain critical applications. One of the limitations of the aforementioned TDR devices is the perceived minimum system rise time for these prior art devices. It should be understood that the total rise time consists of the combined rise time of the driving pulse, and that of the oscilloscope, or other electrical sampling device which monitors the returning electrical reflections. Still further, these same prior art devices which have been utilized, heretofore, to determine and detect these reflected electrical signals have often been difficult to deploy outside a laboratory environment because of their size or complexity, or on the other hand, have repeatedly shown that they are less than accurate regarding detecting various electrical conditions in the transmission, multi-conductor or data transfer cable, which is being studied or tested. Further, these same prior art TDR devices, and the electrical traces they produce are often very difficult to interpret except for the most skilled technicians. Moreover, and while, in theory, the distance to an electrical problem that a multi-conductor or data transfer cable may have can be calculated or otherwise determined from a reflected electrical signal which is received from the multi-conductor or data transfer cable, this calculation has often-times proved more difficult to accurately calculate than what the available prior art information on this subject matter would tend to suggest.
Therefore, a method for detecting an operational condition of a multi-conductor or data transfer cable which avoids the shortcomings attendant with the prior art devices and methodology used heretofore, is the subject matter of the present invention.